h8s-2646 Renesas Electronics Corporation., h8s-2646 Datasheet - Page 719

• Manufacturer Part Number: h8s-2646
• Description: Renesas 16-bit Single-chip Microcomputer H8s Family/h8s/2600 Series
• Manufacturer: Renesas Electronics Corporation.

The flash memory itself cannot be read while the SWE bit is set to 1 to perform programming or
erasing, so the control program that performs programming and erasing should be run in on-chip
RAM or external memory. When a program is in external memory, an instruction for writing to
flash memory and the following instruction must be in the on-chip RAM.
Figure 20.9 shows the procedure for executing the program/erase control program when
transferred to on-chip RAM.
Note: * Do not apply a constant high level to the FWE pin. Apply a high level to the FWE pin
only when the flash memory is programmed or erased. Also, while a high level is
applied to the FWE pin, the watchdog timer should be activated to prevent
overprogramming or overerasing due to program runaway, etc.
For more information on FWE application/cancel, refer to section 20.13, Flash
Memory Programming and Erasing Precautions.
Figure 20.9 User Program Mode Execution Procedure
Write the FWE assessment program and
transfer program (and the program/erase
control program if necessary) beforehand
Branch to flash memory application
program (flash memory rewriting)
Branch to program/erase control
Transfer program/erase control
Execute program/erase control
MD2, MD1, MD0 = 110, 111
program in RAM area
program to RAM
FWE = high*
Clear FWE
Reset-start
program
Rev. 5.00 Sep 22, 2005 page 693 of 1136
REJ09B0257-0500
Section 20 ROM